From b8052176db03f5d357ca50adf1e90cfecccbc001 Mon Sep 17 00:00:00 2001
From: Tamir Duberstein <tamird@google.com>
Date: Tue, 25 May 2021 11:38:33 -0700
Subject: Use the stack RNG

Remove redundant interface.

PiperOrigin-RevId: 375756254
---
 pkg/tcpip/network/ipv6/ipv6.go |  1 -
 pkg/tcpip/network/ipv6/ndp.go  |  5 ++---
 pkg/tcpip/stack/nud.go         | 11 +++--------
 pkg/tcpip/stack/nud_test.go    | 13 ++++++++-----
 4 files changed, 13 insertions(+), 17 deletions(-)

(limited to 'pkg/tcpip')

diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 68f8308f2..35d125a53 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -184,7 +184,6 @@ type endpoint struct {
 	nic        stack.NetworkInterface
 	dispatcher stack.TransportDispatcher
 	protocol   *protocol
-	stack      *stack.Stack
 	stats      sharedStats
 
 	// enabled is set to 1 when the endpoint is enabled and 0 when it is
diff --git a/pkg/tcpip/network/ipv6/ndp.go b/pkg/tcpip/network/ipv6/ndp.go
index 11ff36561..7af5e6975 100644
--- a/pkg/tcpip/network/ipv6/ndp.go
+++ b/pkg/tcpip/network/ipv6/ndp.go
@@ -16,7 +16,6 @@ package ipv6
 
 import (
 	"fmt"
-	"math/rand"
 	"time"
 
 	"gvisor.dev/gvisor/pkg/sync"
@@ -1718,7 +1717,7 @@ func (ndp *ndpState) startSolicitingRouters() {
 	// 4861 section 6.3.7.
 	var delay time.Duration
 	if ndp.configs.MaxRtrSolicitationDelay > 0 {
-		delay = time.Duration(rand.Int63n(int64(ndp.configs.MaxRtrSolicitationDelay)))
+		delay = time.Duration(ndp.ep.protocol.stack.Rand().Int63n(int64(ndp.configs.MaxRtrSolicitationDelay)))
 	}
 
 	// Protected by ndp.ep.mu.
@@ -1861,7 +1860,7 @@ func (ndp *ndpState) init(ep *endpoint, dadOptions ip.DADOptions) {
 
 	header.InitialTempIID(ndp.temporaryIIDHistory[:], ndp.ep.protocol.options.TempIIDSeed, ndp.ep.nic.ID())
 	if MaxDesyncFactor != 0 {
-		ndp.temporaryAddressDesyncFactor = time.Duration(rand.Int63n(int64(MaxDesyncFactor)))
+		ndp.temporaryAddressDesyncFactor = time.Duration(ep.protocol.stack.Rand().Int63n(int64(MaxDesyncFactor)))
 	}
 }
 
diff --git a/pkg/tcpip/stack/nud.go b/pkg/tcpip/stack/nud.go
index 02f905351..dac94cbe4 100644
--- a/pkg/tcpip/stack/nud.go
+++ b/pkg/tcpip/stack/nud.go
@@ -16,6 +16,7 @@ package stack
 
 import (
 	"math"
+	"math/rand"
 	"sync"
 	"time"
 
@@ -313,15 +314,9 @@ func calcMaxRandomFactor(minRandomFactor float32) float32 {
 	return defaultMaxRandomFactor
 }
 
-// A Rand is a source of random numbers.
-type Rand interface {
-	// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
-	Float32() float32
-}
-
 // NUDState stores states needed for calculating reachable time.
 type NUDState struct {
-	rng Rand
+	rng *rand.Rand
 
 	mu struct {
 		sync.RWMutex
@@ -342,7 +337,7 @@ type NUDState struct {
 
 // NewNUDState returns new NUDState using c as configuration and the specified
 // random number generator for use in recomputing ReachableTime.
-func NewNUDState(c NUDConfigurations, rng Rand) *NUDState {
+func NewNUDState(c NUDConfigurations, rng *rand.Rand) *NUDState {
 	s := &NUDState{
 		rng: rng,
 	}
diff --git a/pkg/tcpip/stack/nud_test.go b/pkg/tcpip/stack/nud_test.go
index 6ba97d626..d85213fba 100644
--- a/pkg/tcpip/stack/nud_test.go
+++ b/pkg/tcpip/stack/nud_test.go
@@ -16,6 +16,7 @@ package stack_test
 
 import (
 	"math"
+	"math/rand"
 	"testing"
 	"time"
 
@@ -46,12 +47,14 @@ type fakeRand struct {
 	num float32
 }
 
-var _ stack.Rand = (*fakeRand)(nil)
+var _ rand.Source = (*fakeRand)(nil)
 
-func (f *fakeRand) Float32() float32 {
-	return f.num
+func (f *fakeRand) Int63() int64 {
+	return int64(f.num * float32(1<<63))
 }
 
+func (*fakeRand) Seed(int64) {}
+
 func TestNUDFunctions(t *testing.T) {
 	const nicID = 1
 
@@ -708,7 +711,7 @@ func TestNUDStateReachableTime(t *testing.T) {
 			rng := fakeRand{
 				num: defaultFakeRandomNum,
 			}
-			s := stack.NewNUDState(c, &rng)
+			s := stack.NewNUDState(c, rand.New(&rng))
 			if got, want := s.ReachableTime(), test.want; got != want {
 				t.Errorf("got ReachableTime = %q, want = %q", got, want)
 			}
@@ -780,7 +783,7 @@ func TestNUDStateRecomputeReachableTime(t *testing.T) {
 			rng := fakeRand{
 				num: defaultFakeRandomNum,
 			}
-			s := stack.NewNUDState(c, &rng)
+			s := stack.NewNUDState(c, rand.New(&rng))
 			old := s.ReachableTime()
 
 			if got, want := s.ReachableTime(), old; got != want {
-- 
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